How to unlock a locked hard disk?

[joe at actionline.com]

.
There are two identical 300-gig hard disks on my computer;
but only one is accessible. When I do 'df' I see only this:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb5             7.7G  3.5G  3.9G  48% /
/dev/sdb7             138G  9.5G  129G   7% /home

Hardware detection shows two hard disks: sda and sdb:

#1 ‎ATA MAXTOR STM332062
Old device file: ‎/dev/sda
Partitions Primary partitions: ‎1 (sda1)
Misc Geometry: ‎38913/255/63 (CHS)
Disk controller: ‎0 -- Module: ‎sata_nv

#2 ‎ATA MAXTOR STM332062
Old device file: ‎/dev/sdb
Partitions Primary partitions: ‎1 (sdb1)
Extended partitions: ‎3 (sdb5, sdb6, sdb7)
Misc Geometry: ‎38913/255/63 (CHS)
Disk controller: ‎1 -- Module: ‎sata_nv

When I tried to use 'gparted', I see this error:

error: libhal_acquire_global_interface_lock:
org.freedesktop.Hal.Device.InterfaceAlreadyLocked:
The interface org.freedesktop.Hal.Device.Storage is already
exclusively locked either by someone else or by yourself

So, I booted "Part Magic" Linux live CD and screen captured
the contents of the two hard disks as shown at these links:

http://upquick.com/temp/gparted1.png
http://upquick.com/temp/sda.sdb.png

I want to use the second hard disk to backup all my files
on the first hard disk.

What do I need to do to get the second hard disk unlocked
and mounted so I can copy all my files onto it?